语法精讲① 动词不定式作主语和表语
1．动词不定式的时态和语态
2.动词不定式作主语
动词不定式作主语时，一般表示具体的或一次性的动作。作主语的不定式有时态和语态的变化，且谓语动词通常用单数。
To finish this job in one day is impossible.
要在一天之内完成这项工作是不可能的。(表示具体的情况)
动词不定式作主语时，有以下两种形式：
(1)把不定式置于句首
To get there by bike will take us half an hour.
我们骑自行车到那儿需要半个小时。
(2)用it作形式主语，把作真正主语的不定式(短语)后置，常用于以下结构中：
①It ＋be＋名词＋to do sth.
It's our duty to take good care of the old.
照顾好老人是我们的责任。
②It takes sb.＋some time＋to do sth.
How long did it take you to finish the work
你花了多长时间来完成这项工作？
③It＋be＋形容词＋for sb.＋to do sth.
It is difficult for us to finish writing the composition in a quarter of an hour.
在十五分钟内完成这个作文对我们来说太难了。
④It＋be＋形容词＋of sb.＋to do sth.
It is stupid of you to write down everything the teacher says.
你将老师所说的话全部记下来是一种很笨的方法。
[特别注意] 动名词(短语)作主语多表示一般性的、抽象的、重复性的动作或状态。
Reading poems gives me much pleasure.
读诗给我带来很多乐趣。
3．动词不定式作表语
动词不定式(短语)作表语通常用来说明主语的具体内容(职业、职责或性质等)，也可以表示目的、愿望等。
A college counsellor's job is to help students adjust to college life.
大学辅导员的工作是帮助学生适应大学生活。
His ambition is to become an actor.
他的理想是成为一名演员。
[特别注意] ①常见的后接动词不定式(短语)作表语的系动词有appear，seem，prove，remain等。
Our English teacher seems to have known the secret.
我们的英语老师好像已经知道这个秘密了。
Whether we will succeed or not remains to be seen.我们是否会成功仍待观察。
②当主语部分含有实义动词do的某种形式时，不定式(短语)作表语时通常省略to。
All I can do now is keep silent.
我现在所能做的就是保持沉默。
课时达标·随堂自测
Ⅰ.用括号内适当形式填空
1．____________ (see) is to believe.I won't believe it until I see it by myself.
2．As a student in senior high school，the most important task is ____________ (study) hard，which determines your future.
3．Exercise energizes you，so it is more difficult ____________ (relax) and have a peaceful sleep when you are very excited.
4．His plan is ____________ (buy) a new computer for his son as a reward for his good behavior at school.
5．What squirrels can do is ____________ (store) all kinds of nuts before winter comes.
6．It took him a long time ____________ (recover) from a bad cold.
7．As an old saying goes, “It is not wise __________ (judge) a book by its cover.”
8．It's easy for you ____________ (attack) when you are in red in front of a bull (公牛).
9．If the injuries are severe burns，it is vital ____________ (get) the victim to the doctor or hospital at once.
10．Having been lost in the mountains for three days，what the three visitors were able to do was ____________ (expect) the help of rescuers.
Ⅱ.结合不定式的用法完成句子
1．我的愿望是成为一名像爱因斯坦那样的科学家。
My wish is ____________________ like Einstein.
2．作为一名共产党员，我觉得我的职责就是全心全意为人民服务。
As a Communist, I feel my duty is ______________________ heart and soul.
3．要健康地生活，我们有必要进行大量的锻炼。
________________________ to live a healthy life.
4．依我看，成功的关键是不断努力。
From my point of view, the key to success is ____________________________．
语法精讲① 动词不定式作主语和表语
课时达标·随堂自测
Ⅰ.用括号内适当形式填空
1．To see 2.to study 3.to relax 4.to buy 5.(to) store 6.to recover 7.to judge 8.to be attacked 9.to get
10．(to) expect
Ⅱ.结合不定式的用法完成句子
1．to become a scientist 2.to serve the people 3.It is necessary for us to get plenty of exercise 4.to make continuous efforts
21世纪教育网(www.21cnjy.com)(共15张PPT)
语法精讲 ① 动词不定式作主语和表语
1．动词不定式的时态和语态
2.动词不定式作主语
动词不定式作主语时，一般表示具体的或一次性的动作。作主语的不定式有时态和语态的变化，且谓语动词通常用单数。
To finish this job in one day is impossible.
要在一天之内完成这项工作是不可能的。(表示具体的情况)
动词不定式作主语时，有以下两种形式：
(1)把不定式置于句首
To get there by bike will take us half an hour.
我们骑自行车到那儿需要半个小时。
(2)用it作形式主语，把作真正主语的不定式(短语)后置，常用于以下结构中：
①It ＋be＋名词＋to do sth.
It's our duty to take good care of the old.
照顾好老人是我们的责任。
②It takes sb.＋some time＋to do sth.
How long did it take you to finish the work
你花了多长时间来完成这项工作？
③It＋be＋形容词＋for sb.＋to do sth.
It is difficult for us to finish writing the composition in a quarter of an hour.
在十五分钟内完成这个作文对我们来说太难了。
④It＋be＋形容词＋of sb.＋to do sth.
It is stupid of you to write down everything the teacher says.
你将老师所说的话全部记下来是一种很笨的方法。
[特别注意] 动名词(短语)作主语多表示一般性的、抽象的、重复性的动作或状态。
Reading poems gives me much pleasure.
读诗给我带来很多乐趣。
3．动词不定式作表语
动词不定式(短语)作表语通常用来说明主语的具体内容(职业、职责或性质等)，也可以表示目的、愿望等。
A college counsellor's job is to help students adjust to college life.
大学辅导员的工作是帮助学生适应大学生活。
His ambition is to become an actor.
他的理想是成为一名演员。
[特别注意] ①常见的后接动词不定式(短语)作表语的系动词有appear，seem，prove，remain等。
Our English teacher seems to have known the secret.
我们的英语老师好像已经知道这个秘密了。
Whether we will succeed or not remains to be seen.我们是否会成功仍待观察。
②当主语部分含有实义动词do的某种形式时，不定式(短语)作表语时通常省略to。
All I can do now is keep silent.
我现在所能做的就是保持沉默。
课时达标·随堂自测
Ⅰ.用括号内适当形式填空
1．____________ (see) is to believe.I won't believe it until I see it by myself.
2．As a student in senior high school，the most important task is ____________ (study) hard，which determines your future.
3．Exercise energizes you，so it is more difficult ____________ (relax) and have a peaceful sleep when you are very excited.
To see
to study
to relax
4．His plan is ____________ (buy) a new computer for his son as a reward for his good behavior at school.
5．What squirrels can do is ____________ (store) all kinds of nuts before winter comes.
6．It took him a long time ____________ (recover) from a bad cold.
7．As an old saying goes, “It is not wise __________ (judge) a book by its cover.”
to buy
(to) store
to recover
to judge
8．It's easy for you ____________ (attack) when you are in red in front of a bull (公牛).
9．If the injuries are severe burns，it is vital ____________ (get) the victim to the doctor or hospital at once.
10．Having been lost in the mountains for three days，what the three visitors were able to do was ____________ (expect) the help of rescuers.
to be attacked
to get
(to) expect
Ⅱ.结合不定式的用法完成句子
1．我的愿望是成为一名像爱因斯坦那样的科学家。
My wish is ____________________ like Einstein.
2．作为一名共产党员，我觉得我的职责就是全心全意为人民服务。
As a Communist, I feel my duty is _________________ heart and soul.
to become a scientist
to serve the people
3．要健康地生活，我们有必要进行大量的锻炼。
_________________________________ to live a healthy life.
4．依我看，成功的关键是不断努力。
From my point of view, the key to success is ____________________．
It is necessary for us to get plenty of exercise
to make continuous efforts
